[Code of Federal Regulations] [Title 40, Volume 22] [Revised as of July 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR201.21] [Page 73] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 201--NOISE EMISSION STANDARDS FOR TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS--Table of Contents Subpart C--Measurement Criteria Sec. 201.21 Quantities measured. The quantities to be measured under the test conditions described below, are the A-weighted sound levels for ``fast'' or ``slow'' meter response as defined in the American National Standard S1.4-1971.